The literature teaches that aqueous silicone emulsions are dispersions of siloxane polymers in water. Crosslinking of the siloxane polymers may take place either before or after the evaporation of the water although crosslinking prior to the evaporation of water is more common. Upon the evaporation of water, the silicone emulsions produce silicone elastomers in the form of coatings, seals, caulks, etc.
Generally, silicone elastomers from aqueous silicone emulsions have excellent resistance to weathering, moderate high temperature stability and good low temperature properties. Due to their property profile, silicone elastomers from aqueous silicone emulsions find use as sealants, caulks and additives and are used widely in building construction.
One of the many problems which one encounters with constructing a building is how to seal the many openings that occur through normal construction in a manner which will decrease the spread of flame and the movement of smoke from one part of a building to another in the event of a fire. These openings may occur where two or more structural components of the building meet such as wall-floor joints, wall-wall joints, wall-ceiling joints etc., as well as openings in structural components which are made to accommodate objects such as cables, cable trays, conduits, mechanical piping, ducts and the like which necessarily must pass through the ceilings, walls etc.
In addition to needing a composition having smoke and fire resistant properties, another problem is applying the composition. Current techniques for achieving a smoke barrier typically utilize sealants or closed-cell foams which are pumped, gunned or trowelled into the joints. This is a laborious process and in certain cases the joints may be inaccessible to common sealing or application techniques.
One objective of this invention is to prepare an aqueous silicone emulsion which forms a silicone elastomer upon the removal of water having improved smoke and fire resistant properties.
Another objective is to prepare an aqueous silicone emulsion exhibiting pseudo-plastic rheology, which facilitates its application by spraying and permits a uniform film to be applied to vertical or horizontal surfaces without runs or drips.